ABSTRACT Sleep deficiency is a major public health concern. The Centers for Disease Control and Prevention shows that about 20% of American adults have insufficient sleep. Short sleep duration and irregular sleep timing is related to increased risk for health problems ranging from obesity to diabetes to earlier mortality, as well as other problems such increased unintentional injuries and decreased ability to concentrate. Per Healthy People 2020, understanding the burden sleep deficiencies among minority populations is an important public health goal. Filipino Americans are a significant population from which to study sleep because they have relatively high rates of diabetes, obesity, and heart disease, and preliminary studies have suggested that they also have shorter sleep duration compared with African Americans and Whites. A major unanswered question relates to the mechanisms that may drive shorter sleep duration and irregular sleep timing. We hypothesize that stress plays a key role, and that several important mechanisms mediate the association between stressors and sleep disparities. These mechanisms include rumination, diet, physical activity, disrupted routines, and environmental stimuli, such as noise and light. The present study builds on an ongoing 3-year longitudinal study of Filipino American immigrants titled, Health of Philippine Emigrants Study (HoPES; R01HD083574). HoPES is currently in its first year and collects detailed information regarding stressors, diet, physical activity, anthropometrics and biomarkers obtained from dried blood spots. This application seeks to add objective measures of sleep activity via actigraphy, and comprehensive sleep quality questions. We will also study the effects of sunlight variability as another mechanism that may disrupt circadian rhythms. Our study will integrate a biopsychosocial framework from which to longitudinally study sleep patterns of Filipinos (n=832) across the U.S. over 4 years of new data collection. We will also conduct key-informant interviews and re-interviews with 60 participants in 6 cities across the nation to understand the cultural mechanisms that may affect sleep disturbances.